Many modern electronic devices include planar electrical conductors that are formed on a substrate. The electrical conductors are patterned into various shapes or electrical “traces.” In some configurations, the traces electrically connect various components affixed to the substrate, act as antennas for radio transmitters and receivers, and provide a ground plane. Printed circuit boards (PCBs) are a common example of a substrate, typically a polymer layer, with thin traces of electrically conductive materials, such as copper or aluminum, formed on one or both sides of the substrate.
Recent advances in electronics have led to increasingly smaller and less expensive electronic devices used in a growing number of applications. One such device is the radio frequency identifier (RFID) tag. A typical passive RFID tag includes a small microchip that is electrically connected to an antenna. When an RFID tag reader is positioned near the RFID tag, the electrical energy emitted by the reader energizes the microchip in the RFID tag and the RFID tag transmits data from the microchip to the RFID reader. The microchip in the RFID tag is programmed with various product codes or other data that are typically used to identify the object to which the RFID tag is affixed.
The antenna in the RFID tag serves at least two purposes. First, the antenna couples the electrical energy transmitted by the RFID reader to the microchip in the RFID tag. Second, the antenna enables the RFID tag to transmit data back to the RFID reader. In a typical RFID tag, the antenna is an electrical trace formed on a substrate such as plastic.
Processes for manufacturing electrical traces for RFID tags and other electronic devices are known. A typical process completely covers the substrate with a thin metal layer. Next, a layer of resist material is applied to selected portions of the metal layer. The resist material is applied with the same pattern as the desired electrical traces to be formed on the substrate, e.g., in the shape of an antenna. After the resist material is applied, an etching process, which typically includes acid, dissolves any metal that is not covered by the resist material. Care must be taken in selecting a substrate to ensure the substrate is not dissolved by the acid. Additionally, the substrate needs to be substantially non-porous so the acid does not diffuse through the substrate and dissolve metal that is formed under the resist layer. Once the etching process is completed, some or all of the resist material is stripped away to enable the electrical traces to be connected to various electrical components that are placed on the substrate.
The existing techniques for forming electrical conductors and electrical traces on different substrates have drawbacks due to the complexity of the process for forming the electrical traces. For example, existing techniques require an etching process to form the pattern. Additionally, the materials required for existing processes may increase the cost of production for each device or produce environmentally harmful waste. Thus, improved systems and processes for production of electrical conductors on various substrates are beneficial.